Many organizations and governments have the need of supervising what is said over they phone by employees in their organizations to guard against IP theft or guard against liability from saying the wrong thing or leaking confidential information. It is generally impractical to record all calls and analyze them. Furthermore, doing this means that the organization only becomes aware of a problem after it's too late.
Parents have the same problem. They want to give their children freedom by providing them access to a phone, and more frequently now an Internet connection, which enables the use of a PC phone (VoIP). There are many temptations for children that parents can foresee, but monitoring such use is difficult.